【作者】 刘振平；

【导师】 贺怀建；

【作者基本信息】 中国科学院研究生院（武汉岩土力学研究所） ， 岩土工程， 2010， 博士

【摘要】 工程地质三维建模是3DGIS在地学领域的一个发展分支,有很强的专业应用背景,已经成为计算机科学、岩土工程等多学科交叉领域研究的前沿和热点；同时为了进一步考察人类活动(开挖、开采等)产生的影响,工程师们更希望已经建立的地质三维模型不仅能“看”而且根据一些力学原理还能“算”,而这也是研究中的一个难点。基于此,本文就工程地质建模与计算的可视化方法中的若干关键问题进行了深入地研究,主要体现在以下几个方面：(1)基于AQE数据结构,建立了BRep与空间分解相结合的三维地质模型结构。通过对线框、表面、实体模型进行分析,最后将边界表示模型(BRep)作为主要建模方法,主要原因：①BRep几何模型是线框模型、表面模型以及空间分解等模型的纽带,通过BRep可以容易地实现彼此之间相互转换；②BRep模型可以比较精确地表达地物的形状,建模效率高。与此同时,为了实现地质体的精细表达,还将单元分解模型作为一种辅助建模手段。经过对表示BRep模型几种数据结构的对比、分析,发现AQE数据结构更适合于地质体计算模型的构建,因为它既能用于物体各个表面之间的组织,也能建立实体单元之间的拓扑联系,同时还保存了图形的对偶图信息。因此,基于AQE数据结构,给出了三维地质体数据模型,实现了DT剖分、面面裁剪以及缝合等运算操作。(2)基于GK-Kriging插值算法的快速三维地质建模方法。主要建模步骤为：首先通过GA-Kriging方法得到包含地层编号属性的规则或不规则数据点,然后在VTK中直接对这些点进行Delaunay四面体剖分或者直接生成六面体,最后以云图的形式实现对不同地层的表达以及任意剖切面的提取。这种方法的主要特点就是将地层编号作为插值属性,同时它免去了一般方法中判断、求取地层切割面的繁琐过程,是一种直观、简单、自动化的建模手段。(3)基于TIN面的三角形网格剖分以及有限元开挖模拟。引入Delaunay优化算法,在CDT基础上实现了能用于有限元计算的三角剖分网格,在一定程度上实现了可视化模型TIN三角形面片与FEM计算网格的统一；网格剖分可以通过三个约束条件来控制,最小角度、最大面积以及是否具备Delaunay特性；其中具备Delaunay特性的三角形网格更适合于FVM以及流体方面的数值模拟。编写了三角形平面应力、应变单元的有限元计算模块,根据求得的开挖边界单元上的等效释放节点力实现了开挖模拟。(4)基于三维地质模型实现了基桩承载力计算与小应变曲线模拟。对桩与TIN地层面之间位置关系的确定给出了相应的算法；基于英国BS标准以及德国的DIN规范,实现了桩基承载力的计算；根据桩土相互作用模型,依据Newmark算法得到了桩基完整性检测中小应变的模拟曲线。(5)基于Python复合开发平台,并且对3DPyGeoMA系统进行了研发。为了实现系统的快速开发,提出了将Python语言作为“粘合剂”的复合开发平台,核心思想就是：Pyhton语言作为粘合剂来调用其它语言编写的模块或者Python自己的库函数。文中给出了平台的框架图以及实现步骤,并且在此平台的基础上选择VTK为可视化接口,对3DPyGeoMA系统进行了研发。同时基于GDAS中间件技术实现了B/S结构三维地质信息系统。通过在公路边坡、地铁以及重力大坝工程实例中的应用,对系统在三维建模、漫游、数值计算以及计算结果后处理方面功能进行了初步检验,证明了系统开发方法的可行性以及相关理论的有效性。更多还原

【Abstract】 The 3D engineering geological modeling is one branch of 3DGIS in geology, whose application is mainly under geological professional background. It has been the interdisciplinary frontier and hot point of geosciences, computer science and etc; Moreover, for the purpose on figuring out the influences for human activities (such as excavation, mining and so on), the engineers hope the existing 3D geological model can be used not only for displaying but also for calculation according to some mechanics principle, which is also the difficulty in research. So some key problems of 3D geological modeling and calculation are discussed in this paper, which are mainly including several aspects listed below.(1) The development of 3D geological model combining BRep(Boundary Representation) and element decomposition model based on AQE data structure.BRep model is used as the primary modeling way through the comparison among wireframe, surface, and the other solid models. There are mainly two reasons, on one hand it is the tie of other models, the mutual transformation of BRep and one of the other model is available; On the other hand, it can be used to represent geological object surface shape in accuracy and efficiency. Moreover, in order to describe geological body precisely, element decomposition model is introduced as the auxiliary modeling method.AQE data structure is more appropriate for geological model which can be applied to calculation by the analysis of other data structures expressing BRep model. Because it can be used to organize structures among surfaces and establish topological relationships among solids. In the end, the 3D geological model is developed and some algorithms involving DT decomposition, clipping and sewing between surfaces are implemented based on AQE data structure.(2) The fast 3D geological modeling method based on GA-Kriging interpolation algorithmThis method mainly consists of 3 steps. First of all, the regular and irregular point datum containing soil stratum attribute number by GA-Kriging interpolation; Secondly, using these points Delaunay tetrahedrons or hexahedrons are generated with VTK; At last, the stratum can be displayed and extracted in the form of soil attribute number cloud map of geological body or some cutting planes. Main characteristic of the method is the interpolation for soil stratum attribute number and the complex procedures of judgment and clipping calculation of different surfaces in other stratum modeling methods. Therefore, the method is automatic and easy to be implemented.(3) Triangular mesh generation based on TIN surface and the implementation of excavation simulation by FEMThe FEM triangular mesh is generated based on CDT(Conforming Delaunay Triangulation) through introducing Delaunay refinement algorithm, which made the TIN for visualization and FEM computational grid unified; There are 3 constrain condition for triangular decomposition including minimum angle and maximum area of every triangle and whether every triangle conforms to Delaunay attribute. Furthermore, the CDT(Conforming Delaunay Triangulation) mesh is more suitable for the application on FVM and fluid numerical simulation.The algorithm of triangular planar strain and stress element is programmed, and excavation simulation is implemented by obtain equivalent nodal released force on the excavation boundary.(4) The calculation of pile bearing capability and low strain curve simulationFirstly, the algorithm to determine the special relation between pile and stratum is presented; Secondly, the calculation for the pile bearing capacity is accomplished by BS(British Standard) and German specification of DIN; In the end, based on the pile-soil interaction model, the simulated low strain curve is achieved using Newmark algorithm.(5) The developments and applications of the system so-called 3DPyGeoMA based on Python composite platformIn order to improve the efficiency of system development, a kind of composite development platform is proposed which uses Python language as binder. Its core idea is calling other models programmed by C、C++ or Fortran language by Python. Moreover, the structure frame and the concrete implementation procedures are put forward in this paper. Furthermore, the VTK is selected as visual interface and the B/S structured 3D geological information system is established based on the technology of middleware.At last the system is used in highway slope, subway and hydropower projects 3D geological modeling, navigation, calculation and analysis, the results show the feasibility of system development method and validity of the basic theories presented in this paper.更多还原